1. Field of the Invention
The invention relates to ceramic compositions, and in particular to ceramic powder composition utilized in passive devices.
2. Description of the Related Art
Ceramic materials with a main component of titanate are typically utilized as a dielectric of a conventional laminated ceramic condenser. The titanates become semiconductors due to reductive reaction thereof during sintering thereof under neutral or reductive atmosphere. Thus, the titanates are typically sintered under an oxidized atmosphere. As a result, it is necessary for inner electrodes of the condenser to have a melting point higher than the sintering temperature and to not oxidize under an oxidized atmosphere. It is thus necessary to utilize noble metals such as Pd or Pt as the inner electrodes, substantially increasing process cost of the laminated ceramic condenser.
Kojima et al. disclose a non-reductive ceramic material having a main component represented by [(CaxSr1−x)O]m[(TiyZr1−x)O2], wherein x is between 0 and 1, y is between 0 and 0.10, and m is between 0.75 and 1.04, and an auxiliary component containing 0.2-5 mol % (calculated MnO) of Mn oxide, 0.1-10 mol % (calculated as Al2O3) of Al oxide and 0.5-15 mol % of a component of [(BazCa1−z)O]vSiO2, wherein z is between 0 and 1, and v is between 0.5 and 4.0 in U.S. Pat. No. 6,118,648. The sintering temperature of the ceramic material does not exceed 1300° C., and Ni, having a melting point of 1455° C., can be utilized as inner electrodes.
With development of high-frequency components, the inner electrodes thereof require materials with low impedance such as Cu having a melting point of 1085° C. Kojima et al., however, do not disclose the technology to lower the sintering temperature below 1085° C., and thus, it is difficult to introduce copper inner electrodes to the ceramic materials disclosed by Kojima et al.